Unit 47

Longitudinal dune

Long, ridge-like sand dune that migrates in a direction parallel to the ridge crest, often formed as a result of strong winds from two directions

Surface creep

Movement of fairly large rock fragments by the wind actually pushing them along the ground,

Eolian

Pertaining to the action of the wind

Saltation

Process in which sediment is moved by stream flow or wind; sand and gravel can saltate in a stream, while the wind generally moves only sand-sized particles in saltation

Deflation

Process whereby wind erodes the land surface and carries away the eroded material; may produce basins and troughs

Transverse dune

Ridge-like sand dune in which the ridge crest is oriented at a right angle to the prevailing direction of strong winds; usually straight or slightly curved

Erg

Sand sea; large expanse of sandy desert landscape

Deflation hollow

Shallow desert basin created by the wind erosion process of deflation

Ripples

Small, regularly spaced ridges on the surface of a dune or streambed, usually less than 1 cm high on a dune, but sometimes larger on streambeds

Desert pavement

Smoothly weathered, varnish-like surface of closely packed pebbles that has developed on the upper part of an alluvial fan or bajada, no longer subject to stream deposition

Yardangs are formed when wind

cuts troughs into soft bedrock leaving a ridge of rock, desert structure

The following is an erosional landform produced by winds:

deflation hollows, desert pavement, yardang

The points or horns of a barchan dune point

downwind

Loess deposits are from

dust blown from glacial deposits

Dune

Accumulation of sand that is shaped by wind action

Barchan

Crescent-shaped sand dune with low arms or "horns" pointing downwind. Convex side is the windward side

Loess

Deposit of dust laid down after having been blown by the wind; mostly made up of silt grains, formed by productive soils, can stand in steep vertical walls.

Wind abrasion

Erosion of rock surfaces by windborne sand particles

Slip face

Leeward slope of a sand dune

Barchans form in areas with strong unidirectional winds and a limited sand supply

True

Generally, the highest part of the dune is the

crest

Crescent-shaped sand dunes that form along coastlines with some vegetation are called __ dunes

parabolic

Transverse dunes are aligned

perpendicular to wind direction

In a sandstorm, ___ is the dominant mode of particle movement

saltation

These particles are more easily moved by wind

sand with a diameter of about 0.1 mm

Sand grains are deposited on the ________ producing crossbeds as the sand dune migrates

slipface

Dunes covered by vegetation probably indicates that the dune is

unstable